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Tuesday, March 5, 2013

Civil Service Commission Professional or Sub-Professional Reviewer - Page 77/159

Mathematics Test II Solution - Page 77

33. Two countries produce 1/8 and 3/10 respectively of the world production of aluminum. What fraction of the world production do the two nations produce together?

N =  1  +  3 
        8     10

    =  5  +  12 
       40     40

    =  17  *Ans
        40

34. Of 20 is 25 % of x + 7, then x = ________?

25 % ( x + 7 ) = 20

1/4 ( x + 7 ) = 20

x + 7 = 20 x 4

x + 7 = 80

x = 80 - 7

x = 73 *Ans.

35. If 5 x 5 x Z = 15 x 15 x 15, then Z = _________?

5 x 5 x Z = 15 x 15 x 15

Z =  15 x 15 x 15 
             5 x 5

Z = 3 x 3 x 15

Z = 135 *Ans.

36. The morning class in school begin at 8:05 AM and end at 12:00 noon. There are five class periods of 45 minutes each with equal intervals between classes. How many minutes are there in each interval?

Let x - be the length of time of each interval

8: 05 AM       +      : 45 min-class      +      x     +    :45 min-class      +     x     +    :45 min-class     +    x
+   :45 min-class     +      x      +     :45 min-class       =      12:00

8:05 + 5(45 minutes) + 4x    =  12:00

8:05 + 225 minutes + 4x       =  12:00

8:05 + 3 hrs & 45 min + 4x  =  12:00

11:50 + 4x = 12:00

4x = 10 minutes

x = 10 / 4

x = 2.5 minutes *Ans.

Civil Service Reviewer Post 77/159